Exhaust emission control system of internal combustion engine

Abstract

An exhaust emission control system capable of enhancing a purifying performance by increasing a catalyst temperature rising speed (warm-up speed) after starting the internal combustion engine, includes a box body formed with an exhaust gas inlet and an exhaust gas outlet, a catalyst support incorporated into the box body, and a catalyst substance supported on the catalyst support. A part of the catalyst support of the exhaust gas purifying catalyst is a low resistance area formed so that a gas flow resistance is lower than in other areas. The low resistance area is disposed in such a position that a flow velocity of the exhaust gas flowing to the catalyst support is high. A temperature rising speed in the low resistance area is increased, and a temperature rising characteristic is further enhanced with this low resistance area serving as a high density support area for supporting a larger quantity of a catalyst substance such as platinum etc than in other areas.